Pulse generator for energy discharge system

ABSTRACT

This disclosure relates to a pulse generator for triggering successive energy discharges, such as in automotive and other ignition systems and the like, which generator basically comprises a magnet core carrying coil windings on two portions immediately adjacent opposite sides of an air gap, the air gap being interrupted periodically by a conductive slotted vane to alter the coupling between these coil windings. The windings are interconnected with a network containing amplifying means, preferably a pair of transistors, to produce a single output pulse each time the conductive portion of the vane leaves the gap between the windings, the circuit being particularly adapted to work with physically small parts over a wide range of component values, supply voltages and temperatures, and giving accurate angular resolution which is insensitive to the values of the active electronic components.

United States Patent Minks et a1.

[ Sept. 24, 1974 PULSE GENERATOR FOR ENERGY DISCHARGE SYSTEM [76] Inventors: Floyd M. Minks, Rt. 1, Box 66,

Kissimmee, Fla, 32741; Floyd A. Minks, Box 252, Ridgetop, Tenn. 37152 [22] Filed: Sept. 17, 1971 [21] Appl. No.: 181,445

[52] US. Cl. 123/148 E, 123/146.5 A [51] Int. Cl. F02p 3/02 [58] Field of Search 123/148 E, 149 R, 149 D, l23/l46.5 A

[56] References Cited UNITED STATES PATENTS 3,264,521 8/1966 Huntzinger et al 123/148 E 3,277,340 10/1966 .lukes et al. 123/148 E 3,299,874 l/l967 Elkind 123/148 E 3,361,123 1/1968 Kassama et al. l23/l48 E 3,395,685 8/1968 Minks et a1. 123/148 E 3,424,142 l/l969 Nilssen et al..... 123/148 E 3,549,944 12/1970 Minks 123/148 E 3,613,654 10/1971 Gilbert 123/148 E Primary ExaminerLaurence M. Goodridge Assistant ExaminerCort Flint Attorney, Agent, or Firm-Rines and Rines; Shapiro and Shapiro 57 ABSTRACT This disclosure relates to a pulse generator for triggering successive energy discharges, such as in automotive and other ignition systems and the like, which generator basically comprises a magnet core carrying coil windings on two portions immediately adjacent opposite sides of an air gap, the air gap being interrupted periodically by a conductive slotted vane to alter the coupling between these coil windings. The windings are interconnected with a network containing amplifying means, preferably a pair of transistors, to produce a single output pulse each time the conductive portion of the vane leaves the gap between the windings, the circuit being particularly adapted to work with physically small parts over a wide range of component values, supply voltages and temperatures, and giving accurate angular resolution which is insensitive to the values of the active electronic components.

9 Claims, 1 Drawing Figure Ili PAIENT0 3. 837. 325

v TO DISCHARGE GAP SCR

INVENTORS FLOYD M. MINKS FLOYD A. INKS ATTORNEYS PULSE GENERATOR FOR ENERGY DISCHARGE SYSTEM The present invention relates to pulse generating circuits for reliably producing pulses, being more specifically directed to generating pulses for discharging stored energy into discharge gaps such as those employed, for example, in vehicular and other ignition systems and the like.

Previous pulse-producing systems involving conductive vanes employed to gate oscillator circuits for somewhat similar purposes are described, for example, in my prior U.S. Pat. Nos. 3,395,685; 3,435,265 and 3,549,944. In the system of US. Pat. No. 3,395,685, a gated oscillator employing negative feedback is used to control a switching network. While this is suitable in certain applications, several disadvantages have become apparent in those cases where small size of equipment is required and where insensitivity to critical component selection is desirable. The inherently insufficient negative feedback of such circuits, indeed, necessitates the use of two separate cores completely isolated by the moving vane member, producing a physically relatively large, difficult-to-mount and expensive structure. With the gated oscillator output connected to the input of an electronic switch, unless components are very critically selected, a series 'of unwanted pulses may be produced at slow rates of rotation of the control vane. This approach, moreover, is quite sensitive to interference, such as transients on the supply lines and to variations in component parameters with temperature.

Some of these limitations are at least partially overcome in the system of my said US. Pat. No. 3,435,265, though the system thereof is subjected to the same disadvantageous requirement of two separate cores isolated completely by a relatively large disk vane. A blocking oscillator, however, has been substituted for the electronic switch, thus greatly reducing the critical dependence upon component parameters and also greatly reducing the possibility of a series of pulses occurring at low rotational speed. The principal disadvantages of this approach reside in the aforementioned requirement for relatively large and intricate separate coils and in the fact that only a limited amount of power may be fed into the blocking oscillator to prevent lock-on, that may cause the gated oscillator to lose control. This imposes a severe limitation upon the maximum rotational speed of the timing disk vane.

In the concept shown in my US. Pat. No. 3,549,944, a somewhat different circuit concept is employed that, while it does not require a temperature or component sensitive network, it does apply the output of the gated oscillator to control a triggered blocking oscillator, which, unfortunately, is rather sensitive to stray transients on the power supply or other connecting leads and to component values and temperature. This oscillator, furthermore, after it is triggered, must in turn trigger an output control rectifier switch to discharge the energy on the storage capacitor produced by the previous cycle of this triggered blocking oscillator. As a result of the triggered oscillator also supplying the gate pulse to the control rectifier, however, several severe limitations are prevalent. If the input voltage from the source decreases, then there may be insufficient gate drive to the control rectifier. On the other hand, if the input voltage increases, the input circuit of the control rectifier may be damaged. Since some stray capacity will always exist across the windings of the transformer of the triggered oscillator, it is very difficult, moreover. to prevent an undesirable ringing at the end of the energy storage cycle from immediately and prematurely gating on the output switch or control rectifier.

An object of the present invention, accordingly, is to provide a new and improved pulse generating system that shall not be subject to the above-described disadvantages, and, that shall not employ either a gated oscillator or a subsequent electronic switching stage or a triggering oscillator that both charges the storage capacitor and controls the initiationof the trigger device.

It is a further object to provide such a novel system using only a single magnetic core structure readily mounted near a small and easily constructed control vane, with the entire assembly being light and small enough to be moved in confined spaces by actuating mechanisms of very limited energy, such as the vacuum advance mechanism in an automotive distributor or the like.

A further object is to provide a novel impulseproducing circuit of this character of more general utility, as well.

Other and further objects will be explained hereinafter and are more specifically pointed out in the appended claims. In summary, from one of its aspects, the invention contemplates in an ignition system and the like, a two-stage pulse-generating oscillator having a pair of common-core windings, one connected with each stage the core having a gap through which a conductive toothed vane is disposed to rotate to control the coupling between said windings in order to control the commencement and cessation of oscillation impulses in the oscillator, means for periodically storing energy, and electronic switch means responsive to triggering by said oscillation impulses for periodically discharging the periodically stored energy in order to generate therefrom successive discharge impulses for ignition.

The invention will now be described with reference to the accompanying drawing, the single FIGURE of which is a schematic circuit diagram illustrating the application of the invention to the triggering of a discharge gap, such as, for example, the ignition gap in an automotive engine or the like.

Referring to the drawing, the pulse generating system is shown comprising a two-stage transistor oscillator, having transistors I and II associated with windings W1 and W2 and a capacitor C. In accordance with the invention, the windings W1 and W2 may be formed about a single, small C-shaped magnetic core with a small gap therebetween within which a conductive vane V, carrying open slots like gear teeth, may be rotated in the direction of the arrow. As will later be made evident, in accordance with a specific form of the present invention, these windings W1 and W2 are very closely spaced immediately adjacent the gap and on a very small-dimensioned core structure, unlike the prior oscillator windings before-discussed. In addition, as hereinafter pointed out, great precision in terms of the timing of commencement and cessation of oscillations effected by the rotation of the vane V results from this construction. The right-hand terminal of thewinding W1, wound close to the upper free end of the C.-shaped core, is connected to the base l of the transistor stage I and through a bias resistor R1 to the positive input terminal The other terminal of the winding W1 is connected through a pair of stabilizing diodes D to the ground terminal G. The right-hand terminal of the other winding W2, wound close to the lower free end of the C-shaped core, is connected to the base 1' of the transistor stage II of the oscillator, with the opposite terminal of the winding being shown connected also to the ground terminal G. The oscillator capacitor C is connected from the base I to ground.

As the level of AC voltage changes, the gain of transistor II increases, whereas the gain of transistor I remains essentially constant, such that transistor II acts as part of the overall amplification of the oscillator circuit and not merely as a switch, as in some of my said prior patents.

The resistor RI supplies a current through the negligible DC impedance of winding W1 through the elements D to ground G. Thus, as is well known, the voltage drop across D is relatively insensitive to current and remains stabilized at approximately 1.4 volts, so positively biasing the transistor I with respect to ground. The emitter is shown connected by resistor R2 to the base I of transistor II. Transistor II, however, has both its base l and emitter 2 connected to different points of winding W2, such that, with no average or DC voltage existing across the low resistance of this winding, transistor II is normally biased in the cutoff region. There is also a difference between the collector supply impedance available to both transistors. The collector 3 of transistor I is connected directly to the positive supply, whereas collector 3 of transistor II is connected through a relatively high-current limiting resistor R3 to the positive supply, drastically limiting the current of this stage through the resistor. Since, however, the collector 3 is also connected to the capacitor C, a resulting relatively high-current pulse or spike can be conducted from the capacitor C through the collector 3 by way of a path completed through the resistor R4 and the driven output load connected to lead 5. The transistor II can tend to keep the circuit oscillating, therefore requiring limiting the power which can be fed through R3 to C, this becoming less critical as either the current of transistor I is increased or the negative feedback of the winding Wll driving the transistor base 1 becomes larger. This operation is thus to be distinguished from the operation of a gated oscillator followed by an electronic switch, on the one hand, and the blocking oscillator that is used to trigger the triggering oscillator to do the two functions of charging the storage capacitor and triggering the discharge of the same, as in my said prior patents. As before stated, indeed, the sensitivity and other limitations of such other circuits does not reside in that of the present invention and the present circuit enables the novel small winding and vane structure, as well.

Lead 5 is shown for purposes of illustration as connected through a transformer T (to provide the appropriate polarity) to the gate of an SCR or similar solidstate control rectifier switch, so-labeled, triggered by the generated high-current pulse.

The anode of the SCR is shown connected with an output pulse transformer T2 and to an energy storage capacitor C2. When the SCR is thus gated on triggered on, it controls the discharge of energy from the capacitor C2 to the output load, such as an ignition discharge gap. The capacitor C2 is then recharged from a source of energy as by a resonant charging circuit comprising inductance L and check diode D. Other types of supplies could also be used within the concept of this invention to supply this energy and many other discharge circuits and protective devices therein may also be used in applications requiring specific tailoring of these devices.

Further modifications will also occur to those skilled in this art, and all such being considered to fall within the spirit and scope of the invention as defined in the appended claims.

What is claimed is:

1. In an ignition system and the like, a two-stage pulse-generating oscillator having a pair of commoncore windings disposed on opposing ends of a gap in the core, one connected with each stage, means disposed to rotate through said gap to vary the coupling between said windings in order to control the generation of corresponding oscillation impulses in the oscillator, means for periodically storing energy, and electric switch means responsive to triggering by said oscillation impulses for periodically discharging the periodically stored energy in order to generate therefrom successive discharge impulses for ignition, said two stages comprising transistor amplifiers each having base, emitter and collector electrodes, means for connecting the emitter of one transistor to the base of the other, means for connecting one winding to the base of one transistor, means for connecting the other winding to the base of the other transistor and the emitter thereof to an intermediate point of said other winding, and means for connecting the collectors of the transistors to a bias supply, with the collector of the said other transistor connected to said supply through a limiting resistor.

2. A system as claimed in claim 1 and in which the said other winding is returned to ground, capacitance is connected from the base of the other transistor to ground, and the said one winding is returned to ground through a voltage stabilizing path.

3. A system as claimed in claim I and in which the collector of the said other transistor is connected through capacitance and transformer means to said electronic switch means.

4. A system as claimed in claim 3 and in which the electronic switch means is connected with an output transformer across the energy storage means.

5. In an ignition system or the like, an oscillator comprising an amplifying device having a first electrode the bias of which relative to a second electrode controls the conduction of said device, said amplifying device having an input circuit including a first winding connected between said first electrode and a point of reference potential and having an output circuit including a second winding connected between said second electrode and said point of reference potential such that the entire voltage across said second winding is in series between said second electrode and said point of reference potential, said windings being coupled across a gap for inducing a voltage across said first winding to cause said oscillator to oscillate, and means movable through said gap repetitively to vary the coupling between said windings and correspondingly to control the commencement and cessation of oscillations produced by said oscillator.

6. A system as claimed in claim 5 and in which a resistor is connected between said first electrode and a further point of reference potential thereby to provide amplifying device'is a transistor, said first electrode is the base of the transistor and said second electrode is the emitter of said transistor.

9. A system as claimed in claim 8 and in which said oscillator comprises a second transistor the conduction of which is controlled by said first transistor, said second transistor having means connected to said second winding to vary the current therein depending upon the conduction of said second transistor. 

1. In an ignition system and the like, a two-stage pulsegenerating oscillator having a pair of common-core windings disposed on opposing ends of a gap in the core, one connected with each stage, means disposed to rotate through said gap to vary the coupling between said windings in order to control the generation of corresponding oscillation impulses in the oscillator, means for periodically storing energy, and electric switch means responsive to triggering by said oscillation impulses for periodically discharging the periodically stored energy in order to generate therefrom successive discharge impulses for ignition, said two stages comprising transistor amplifiers each having base, emitter and collector electrodes, means for connecting the emitter of one transistor to the base of the other, means for connecting one winding to the base of one transistor, means for connecting the other winding to the base of the other transistor and the emitter thereof to an intermediate point of said other winding, and means for connecting the collectors of the transistors to a bias supply, with the collector of the said other transistor connected to said supply through a limiting resistor.
 2. A system as claimed in claim 1 and in which the said other winding is returned to ground, capacitance is connected from the base of the other transistor to ground, and the said one winding is returned to ground through a voltage stabilizing path.
 3. A system as claimed in claim 1 and in which the collector of the said other transistor is connected through capacitance and transformer means to said electronic switch means.
 4. A system as claimed in claim 3 and in which the electronic switch means is connected with an output transformer across the energy storage means.
 5. In an ignition system or the like, an oscillator comprising an amplifying device having a first electrode the bias of which relative to a second electrode controls the conduction of said device, said amplifying device having an input circuit including a first winding connected between said first electrode and a point of reference potential and having an output circuit including a second winding connected between said second electrode and said point of reference potential such that the entire voltage across said second winding is in series between said second electrode and said point of reference potential, said windings being coupled across a gap for inducing a voltage across said first winding to cause said oscillator to oscillate, and means movable through said gap repetitively to vary the coupling between said windings and correspondingly to control the commencement and cessation of oscillations produced by said oscillator.
 6. A system as claimed in claim 5 and in which a resistor is connected between said first electrode and a further point of reference potential thereby to provide a path for current in said first winding to said further point of reference potential.
 7. A system as claimed in claim 6 and in which said points of reference potential are terminals of a DC supply.
 8. A system as claimed in claim 7 and in which said amplifying device is a transistor, said first electrode is the base of the transistor and said second electrode is the emitter of said transistOr.
 9. A system as claimed in claim 8 and in which said oscillator comprises a second transistor the conduction of which is controlled by said first transistor, said second transistor having means connected to said second winding to vary the current therein depending upon the conduction of said second transistor. 